1. Field of Invention
The present invention relates to an apparatus for loading and unloading open top railroad cars utilizing a conventional material handling equipment item attached to a slidable structure.
2. Description of the Prior Art
Open top railroad cars are widely used to transport a variety of cargoes. Heretofore, several methods are known for loading and unloading of these cargoes. Loading and unloading operations have been accomplished by mobile or stationary cranes positioned adjacent to the area of railroad cars.
However, it is quite common for loading or unloading operations to be conducted far from a depot, yard or other facility where cranes may be used. In such situations, material such as railroad ballast and cross-ties must be loaded or unloaded by manual labor or by methods employing specialized machinery.
The use of hand labor is normally costly and time consuming. However, a specifically designed loading or unloading machine requires a considerable capital expenditure.
U.S. Pat. No. 4,099,635 issued to Leonard, et al, 7/78, discloses a gondola car loader. The apparatus would be prohibitively expensive to manufacture. It could be used only for loading or unloading gondola cars. It would also require special lifting equipment to position the apparatus atop the railroad car.
U.S. Pat. Nos. 4,190,394, 2/80 and 4,175,902, 11/79 issued to Herzog, et al, discloses a method and an apparatus, respectively, for loading and unloading railroad cars utilizing a backhoe-loader with rubber tires. The apparatus positions the operator and controls in the center of the railcar. The apparatus is also limited to a 180 degree swing of the boom structure.
U.S. Pat. Nos. 4,830,562, 5/89 and 4,723,886, 2/88, issued to Frederking, discloses an apparatus for loading and unloading railroad gondola cars utilizing a modified hydraulic excavator. This apparatus requires extensive and expensive modification upon the hydraulic excavator undercarriage. It also requires the use of a ramp for mounting or dismounting the railcars.